US20180097242A1 - Design Of Tunnel Cross Section For More Uniformed Contact Pressure Distribution On Metal Bead Seal At The Intersection Between Bead And Tunnel - Google Patents
Design Of Tunnel Cross Section For More Uniformed Contact Pressure Distribution On Metal Bead Seal At The Intersection Between Bead And Tunnel Download PDFInfo
- Publication number
- US20180097242A1 US20180097242A1 US15/285,795 US201615285795A US2018097242A1 US 20180097242 A1 US20180097242 A1 US 20180097242A1 US 201615285795 A US201615285795 A US 201615285795A US 2018097242 A1 US2018097242 A1 US 2018097242A1
- Authority
- US
- United States
- Prior art keywords
- section
- flow field
- bead
- metal
- tunnel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/02—Details
- H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
- H01M8/0258—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
- H01M8/026—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant characterised by grooves, e.g. their pitch or depth
-
- B60L11/1898—
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L50/00—Electric propulsion with power supplied within the vehicle
- B60L50/50—Electric propulsion with power supplied within the vehicle using propulsion power supplied by batteries or fuel cells
- B60L50/70—Electric propulsion with power supplied within the vehicle using propulsion power supplied by batteries or fuel cells using power supplied by fuel cells
- B60L50/72—Constructional details of fuel cells specially adapted for electric vehicles
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/02—Details
- H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
- H01M8/0258—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
- H01M8/0263—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant having meandering or serpentine paths
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/02—Details
- H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
- H01M8/0267—Collectors; Separators, e.g. bipolar separators; Interconnectors having heating or cooling means, e.g. heaters or coolant flow channels
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/02—Details
- H01M8/0271—Sealing or supporting means around electrodes, matrices or membranes
- H01M8/0273—Sealing or supporting means around electrodes, matrices or membranes with sealing or supporting means in the form of a frame
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M8/1007—Fuel cells with solid electrolytes with both reactants being gaseous or vaporised
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
- H01M8/1018—Polymeric electrolyte materials
- H01M8/1039—Polymeric electrolyte materials halogenated, e.g. sulfonated polyvinylidene fluorides
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M2008/1095—Fuel cells with polymeric electrolytes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2250/00—Fuel cells for particular applications; Specific features of fuel cell system
- H01M2250/20—Fuel cells in motive systems, e.g. vehicle, ship, plane
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0065—Solid electrolytes
- H01M2300/0082—Organic polymers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M8/1004—Fuel cells with solid electrolytes characterised by membrane-electrode assemblies [MEA]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02T90/40—Application of hydrogen technology to transportation, e.g. using fuel cells
Definitions
- the present invention is related to fuel cell flow field plates providing uniform seal contact pressure distributions.
- Fuel cells are used as an electrical power source in many applications. In particular, fuel cells are proposed for use in automobiles to replace internal combustion engines.
- a commonly used fuel cell design uses a solid polymer electrolyte (“SPE”) membrane or proton exchange membrane (“PEM”) to provide ion transport between the anode and cathode.
- SPE solid polymer electrolyte
- PEM proton exchange membrane
- PEM fuel cells In proton exchange membrane (“PEM”) type fuel cells, hydrogen is supplied to the anode as fuel, and oxygen is supplied to the cathode as the oxidant.
- the oxygen can either be in pure form (O2) or air (a mixture of O2 and N2).
- PEM fuel cells typically have a membrane electrode assembly (“MEA”) in which a solid polymer membrane has an anode catalyst on one face, and a cathode catalyst on the opposite face.
- the anode and cathode layers of a typical PEM fuel cell are formed of porous conductive materials, such as woven graphite, graphitized sheets, or carbon paper to enable the fuel to disperse over the surface of the membrane facing the fuel supply electrode.
- the ion conductive polymer membrane includes a perfluorosulfonic acid (“PFSA”) ionomer.
- PFSA perfluorosulfonic acid
- the MEA is sandwiched between a pair of porous gas diffusion layers (“GDL”), which in turn are sandwiched between a pair of electrically conductive elements or plates referred to as flow fields.
- GDL porous gas diffusion layers
- the flow fields function as current collectors for the anode and the cathode, and contain appropriate channels and openings formed therein for distributing the fuel cell's gaseous reactants over the surface of respective anode and cathode catalysts.
- the polymer electrolyte membrane of a PEM fuel cell must be thin, chemically stable, proton transmissive, non-electrically conductive and gas impermeable.
- fuel cells are provided in arrays of many individual fuel cells in stacks in order to provide high levels of electrical power.
- tunnels intersect with a metal bead for the coolant and the reactants to pass through.
- the tunnels/channels have a nearly square trapezoidal cross-section (i.e., wall angle greater than 45 degrees).
- the flow tunnels/channels cross section are designed by primarily considering the coolant/reactant flow.
- the existence of tunnels causes large contact pressure variation at the intersection between the metal bead and the tunnel.
- the primary function of metal bead is to seal the coolant or reactants from leaking outside from headers.
- the sealing function is provided by the contact pressure on the metal bead. Ideally, uniform contact pressure is the most favorable case. Large contact pressure variation may cause extreme low pressure at certain spot which may cause leaking.
- the present invention provides improved contact pressure having less pressure variation at the intersection between metal bead seals and the flow channels.
- the present invention solves one or more problems of the prior art by providing in at least one embodiment a fuel cell flow field plate providing a uniform contact pressure/seal pressure.
- the flow field includes a first metal plate and a second metal plate.
- the first metal plate defines a first opening for providing a first reactant gas to a fuel cell with a first metal bead surrounds the first opening.
- the first metal bead is an embossment.
- a first plurality of tunnels provides a passage into and out of the first metal bead. Each tunnel of the first plurality of tunnels has an inlet tunnel section that leads to the first metal bead and an outlet tunnel section that extends from the first metal bead to provide the first reactant gas to first reactant gas flow channels defined by the first metal plate.
- the inlet tunnel section and the outlet tunnel section each have a curved cross section with an opened base side.
- the second metal plate is of a similar design. Specifically, the second metal plate defines a second opening for providing a second reactant gas to a fuel cell with a second metal bead that surrounds the second opening.
- the second metal bead is an embossment.
- a second plurality of tunnels provides a passage into and out of the second bead. Each tunnel of the second plurality of tunnels having an inlet tunnel section that leads to the second bead and an outlet tunnel section that extends from the second bead to provide the second reactant gas to second reactant gas flow channels defined by the second metal plate.
- the inlet tunnel section and the outlet tunnel section each haves a curved cross section with an opened base side.
- a fuel cell incorporating the flow fields described herein includes a cathode catalyst layer, an anode catalyst layer, and an ion conducting membrane interposed between the cathode catalyst layer and the anode catalyst layer.
- a first gas diffusion layer is disposed over and adjacent to the cathode catalyst layer and a second gas diffusion layer disposed over and adjacent to the anode catalyst layer.
- a first flow field disposed over and adjacent to the first gas diffusion layer and a second flow field disposed over and adjacent to the second gas diffusion layer.
- the first flow field includes a first metal plate and a second metal plate. The first metal plate defines a first opening for providing a first reactant gas to a fuel cell with a first metal bead surrounds the first opening.
- the first metal bead is an embossment.
- a first plurality of tunnels provides a passage into and out of the first bead.
- Each tunnel of the first plurality of tunnels has an inlet tunnel section that leads to the first bead and an outlet tunnel section that extends from the first bead to provide the first reactant gas to first reactant gas flow channels defined by the first metal plate.
- the inlet tunnel section and the outlet tunnel section each have a curved cross section with an opened base side.
- the second metal plate is of a similar design. Specifically, the second metal plate defines a second opening for providing a second reactant gas to a fuel cell with a second metal bead that surrounds the second opening, the second metal bead being an embossment.
- a second plurality of tunnels provides a passage into and out of the second bead.
- Each tunnel of the second plurality of tunnels having an inlet tunnel section that leads to the second bead and an outlet tunnel section that extends from the second bead to provide the second reactant gas to second reactant gas flow channels defined by the second metal plate.
- the inlet tunnel section and the outlet tunnel section each haves a curved cross section with an opened base side.
- the first flow field is of the same design as the second flow field.
- FIG. 1 provides a schematic illustration of a fuel cell incorporating a flow field defining flow channels with improved pressure distribution
- FIG. 2 is a perspective view of a metal plate used to form a fuel cell flow field
- FIG. 3 is a top view a portion of a flow field defining an opening for inputting or outputting a reactant gases or coolant to a flow field;
- FIG. 4A is a cross section of a metal plate defining a tunnel with a curved cross section
- FIG. 4B is a cross section of a metal plate defining a tunnel with a cross section having two lobes
- FIG. 5A is a cross section of a metal plate defining a tunnel with straight sides and a curved top;
- FIG. 5B is a cross section of a metal plate defining a tunnel with straight sides and two lobes
- FIG. 6 illustrates the basic design of a test coupon that was used to determine the pressures on the metal bead seal for various tunnel cross sections
- FIG. 7A provides a plot of the seal contact pressure for prior art flow channel
- FIG. 7B provides a plot of the seal contact pressure for a flow channel having a round section
- FIG. 7C provides a plot of the seal contact pressure for a flow channel having a low trapezoidal cross section.
- percent, “parts of,” and ratio values are by weight; the description of a group or class of materials as suitable or preferred for a given purpose in connection with the invention implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred; the first definition of an acronym or other abbreviation applies to all subsequent uses herein of the same abbreviation and applies mutatis mutandis to normal grammatical variations of the initially defined abbreviation; and, unless expressly stated to the contrary, measurement of a property is determined by the same technique as previously or later referenced for the same property.
- Proton exchange membrane (PEM) fuel cell 10 includes polymeric ion conducting membrane 12 disposed between cathode catalyst layer 14 and anode catalyst layer 16 .
- Fuel cell 10 also includes flow fields 18 , 20 which define gas flow channels 24 and 26 .
- Gas diffusion layers 28 and 30 disposed between flow fields 18 , 20 and cathode catalyst layer 14 and anode catalyst layer 16 , respectively.
- a fuel such as hydrogen is feed to anode catalyst layer 16 through gas flow channels 26 and an oxidant such as oxygen is feed to cathode catalyst layer 14 through gas flow channels 24 .
- Flow fields 18 , 20 also define cooling channels 32 which are used to flow coolant through the flow field plates.
- flow fields 18 , 20 are each typically formed from two metal plates are provided.
- flow field 18 is formed from channel-defining plates 18 a and 18 b while flow field 20 is formed from channel-defining plates 20 a and 20 b .
- metal plates 18 a , 18 b , 20 a , 20 b have a thickness from about 0.05 mm to 0.5 mm.
- FIG. 1 is an idealized schematic and that gas flow channels 24 and 26 are also formed by embossing plates 18 a , 18 b , 20 a and 20 b .
- FIG. 1 is an idealized schematic and that gas flow channels 24 and 26 are also formed by embossing plates 18 a , 18 b , 20 a and 20 b .
- FIG. 1 is an idealized schematic and that gas flow channels 24 and 26 are also formed by embossing plates 18 a , 18 b , 20
- FIG. 1 also depicts the side sealing of the fuel cell in which peripheral gasket 34 seals to embossments 36 .
- Hydrogen ions are generated by anode catalyst layer 16 migrate through polymeric ion conducting membrane 12 were they react at cathode catalyst layer 14 to form water. This electrochemical process generates an electric current through a load connect to flow field plates 18 and 20 .
- flow fields 18 , 20 are each typically formed from two metal plates are provided.
- flow field 18 is formed from channel-defining plates 18 a and 18 b while flow field 20 is formed from channel-defining plates 20 a and 20 b .
- These channels and other structures are typically formed by stamping.
- the metal plates including a number of openings for input and exhausting reactant gases and coolant.
- FIG. 2 is a perspective view of a metal plate that is typical of the design of embossed plates 18 a , 18 b , 20 a , and 20 b .
- Metal plates 38 , 40 define openings 42 - 52 for introducing or exiting a liquid coolant or reactants to the flow field.
- first metal bead 66 surrounds one or more of openings 42 - 52 .
- First metal bead 66 is an embossment that defines a first channel 70 .
- the liquid coolant flows or reactants through this channel.
- a soft material e.g., elastomer, rubber, foam, etc.
- Plurality of tunnels 68 provides a passage into and out of the first metal bead 66 .
- Each tunnel 68 of the first plurality of tunnels has an inlet tunnel section 72 that leads to the first metal bead 66 and an outlet tunnel section 74 that extends from the first metal bead 66 to provide coolant or reactant gases to flow channels 24 , 26 .
- FIG. 2 also depicts a coolant flow channels 82 which is also defined by an embossment.
- First metal bead 66 surrounds openings 42 - 52 .
- First metal bead 66 is an embodiment that defines a first channel 90 .
- a soft material e.g., elastomer, rubber, foam, etc.
- Plurality of tunnels 68 provides a passage into and out of the channel 80 which is defined by first metal bead 66 .
- Each tunnel 68 of the first plurality of tunnels has an inlet tunnel section 72 that leads to the first channel 90 and an outlet tunnel section 94 that extends from the first channel 80 to provide a reactant gas or coolant to flow channels 24 , 26 .
- FIG. 4A depicts flow tunnel 100 which is formed in any of plates 18 a , 18 b , 20 a , 20 b as set forth above.
- Flow tunnel 100 which has an upper wall that is has a single arc 102 in cross section and an open base 104 .
- FIG. 4A also depicts channel-defining metal bead 106 to which tunnel 100 flows.
- Flow tunnel 100 provides a design for the tunnels of plurality of tunnels 68 of FIG. 3A and of the plurality of tunnels 88 of FIG. 3B .
- the cross section of upper wall 102 is approximated by a section of the circumference of a circle.
- open base width w is from about 0.4 mm to about 3 mm.
- Flow tunnel 100 is also defined by a maximum height which is the perpendicular distance from open base 104 to the top of the channel. In a refinement, the maximum height h is from about 0.1 mm to about 2 mm. When a section of flow tunnel 100 is approximated by a portion of the circumference of a circle, the circle has a radius from about 0.2 to about 3 mm.
- FIG. 4B depicts flow tunnel 110 which is formed in any of plates 18 a , 18 b , 20 a , 20 b as set forth above.
- flow tunnel 110 has a cross section with at least two lobes 112 , 114 .
- Flow tunnel 110 has a base (e.g., imaginary or a wall) and a maximum height which is the perpendicular distance from the open base 104 to the top of the channel.
- FIG. 4B also depicts channel-defining metal bead 116 to which tunnel 110 flows.
- open base width w is from about 0.4 mm to about 3mm.
- the maximum height h is from about 0.1 mm to about 2 mm.
- FIG. 5A depicts a flow tunnel with straight sides and a curved top in cross section.
- flow tunnel 120 has a cross section with an upper curved surface 122 .
- Flow channel 120 has a wall angle ⁇ (i.e., angle between wall 124 and open base 126 ) is from 10 to 80 degrees.
- Flow channel 120 is defined by a base and a maximum height which is the perpendicular distance from the base to the top of the channel.
- FIG. 5A also depicts channel-defining metal bead 128 to which tunnel 120 flows.
- the base width is from about 0.4 mm to about 3 mm.
- the maximum height h is from about 0.1 mm to about 3 mm.
- linear side 124 is from about 0.1 to 3 mm in length.
- FIG. 5B depicts a flow tunnel with straight sides and a multi-lobed top in cross section.
- flow channel 130 has a wall angle ⁇ is from 10 to 80 degrees.
- Flow channel 130 is defined by a base and a maximum height h which is the perpendicular distance from the open base to the top of the channel.
- the open base width w is from about 0.4 mm to about 3 mm.
- the maximum height h is from about 0.1 mm to about 3 mm.
- linear side 124 is from about 0.1 to 3 mm in length.
- the tunnels of FIGS. 4A, 4B, 5A, and 5B have a cross sectional area from about 0.005 to 3 mm 2 .
- the tunnels of FIGS. 4A, 4B, 5A, and 5B have a cross sectional area from about 0.01 to 1 mm 2 .
- the tunnels of FIGS. 4A, 4B, 5A, and 5B have a cross sectional area from about 0.01 to 0.5 mm 2 .
- the cross sectional area of the tunnels can vary along the flow direction. For example, the cross sectional area can be large near the inlet and outlet and small near the metal bead.
- FIG. 6 illustrates the basic design of a test coupon that was used to determine the pressures for various tunnel cross sections. Pressure fields were determined by finite element analysis using a compression height of 100 microns.
- Test coupon 140 includes tunnels 142 and metal sealing bead 144 .
- FIG. 7A provides the pressures in a prior art channel. These channels show a pressure variation range of about 1.83 MPa.
- FIG. 7B provides the pressures in a channel with a round cross section. These channels show a pressure variation range of about 1.66 MPa.
- FIG. 7C provides the pressures in a channel with a short trapezoidal cross section. These channels show a pressure variation range of about 1.18 MPa.
Landscapes
- Engineering & Computer Science (AREA)
- Sustainable Energy (AREA)
- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Power Engineering (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Fuel Cell (AREA)
Abstract
Description
- In at least one aspect, the present invention is related to fuel cell flow field plates providing uniform seal contact pressure distributions.
- Fuel cells are used as an electrical power source in many applications. In particular, fuel cells are proposed for use in automobiles to replace internal combustion engines. A commonly used fuel cell design uses a solid polymer electrolyte (“SPE”) membrane or proton exchange membrane (“PEM”) to provide ion transport between the anode and cathode.
- In proton exchange membrane (“PEM”) type fuel cells, hydrogen is supplied to the anode as fuel, and oxygen is supplied to the cathode as the oxidant. The oxygen can either be in pure form (O2) or air (a mixture of O2 and N2). PEM fuel cells typically have a membrane electrode assembly (“MEA”) in which a solid polymer membrane has an anode catalyst on one face, and a cathode catalyst on the opposite face. The anode and cathode layers of a typical PEM fuel cell are formed of porous conductive materials, such as woven graphite, graphitized sheets, or carbon paper to enable the fuel to disperse over the surface of the membrane facing the fuel supply electrode. Typically, the ion conductive polymer membrane includes a perfluorosulfonic acid (“PFSA”) ionomer.
- The MEA is sandwiched between a pair of porous gas diffusion layers (“GDL”), which in turn are sandwiched between a pair of electrically conductive elements or plates referred to as flow fields. The flow fields function as current collectors for the anode and the cathode, and contain appropriate channels and openings formed therein for distributing the fuel cell's gaseous reactants over the surface of respective anode and cathode catalysts. In order to produce electricity efficiently, the polymer electrolyte membrane of a PEM fuel cell must be thin, chemically stable, proton transmissive, non-electrically conductive and gas impermeable. In typical applications, fuel cells are provided in arrays of many individual fuel cells in stacks in order to provide high levels of electrical power.
- In the current flow field designs, tunnels intersect with a metal bead for the coolant and the reactants to pass through. Typically, the tunnels/channels have a nearly square trapezoidal cross-section (i.e., wall angle greater than 45 degrees). The flow tunnels/channels cross section are designed by primarily considering the coolant/reactant flow. However, the existence of tunnels causes large contact pressure variation at the intersection between the metal bead and the tunnel.
- The primary function of metal bead is to seal the coolant or reactants from leaking outside from headers. The sealing function is provided by the contact pressure on the metal bead. Ideally, uniform contact pressure is the most favorable case. Large contact pressure variation may cause extreme low pressure at certain spot which may cause leaking.
- Accordingly, the present invention provides improved contact pressure having less pressure variation at the intersection between metal bead seals and the flow channels.
- The present invention solves one or more problems of the prior art by providing in at least one embodiment a fuel cell flow field plate providing a uniform contact pressure/seal pressure. The flow field includes a first metal plate and a second metal plate. The first metal plate defines a first opening for providing a first reactant gas to a fuel cell with a first metal bead surrounds the first opening. The first metal bead is an embossment. A first plurality of tunnels provides a passage into and out of the first metal bead. Each tunnel of the first plurality of tunnels has an inlet tunnel section that leads to the first metal bead and an outlet tunnel section that extends from the first metal bead to provide the first reactant gas to first reactant gas flow channels defined by the first metal plate. The inlet tunnel section and the outlet tunnel section each have a curved cross section with an opened base side. Typically, the second metal plate is of a similar design. Specifically, the second metal plate defines a second opening for providing a second reactant gas to a fuel cell with a second metal bead that surrounds the second opening. The second metal bead is an embossment. A second plurality of tunnels provides a passage into and out of the second bead. Each tunnel of the second plurality of tunnels having an inlet tunnel section that leads to the second bead and an outlet tunnel section that extends from the second bead to provide the second reactant gas to second reactant gas flow channels defined by the second metal plate. The inlet tunnel section and the outlet tunnel section each haves a curved cross section with an opened base side.
- In another embodiment, a fuel cell incorporating the flow fields described herein is provided. The fuel cell includes a cathode catalyst layer, an anode catalyst layer, and an ion conducting membrane interposed between the cathode catalyst layer and the anode catalyst layer. A first gas diffusion layer is disposed over and adjacent to the cathode catalyst layer and a second gas diffusion layer disposed over and adjacent to the anode catalyst layer. A first flow field disposed over and adjacent to the first gas diffusion layer and a second flow field disposed over and adjacent to the second gas diffusion layer. The first flow field includes a first metal plate and a second metal plate. The first metal plate defines a first opening for providing a first reactant gas to a fuel cell with a first metal bead surrounds the first opening. The first metal bead is an embossment. A first plurality of tunnels provides a passage into and out of the first bead. Each tunnel of the first plurality of tunnels has an inlet tunnel section that leads to the first bead and an outlet tunnel section that extends from the first bead to provide the first reactant gas to first reactant gas flow channels defined by the first metal plate. The inlet tunnel section and the outlet tunnel section each have a curved cross section with an opened base side. Typically, the second metal plate is of a similar design. Specifically, the second metal plate defines a second opening for providing a second reactant gas to a fuel cell with a second metal bead that surrounds the second opening, the second metal bead being an embossment. A second plurality of tunnels provides a passage into and out of the second bead. Each tunnel of the second plurality of tunnels having an inlet tunnel section that leads to the second bead and an outlet tunnel section that extends from the second bead to provide the second reactant gas to second reactant gas flow channels defined by the second metal plate. The inlet tunnel section and the outlet tunnel section each haves a curved cross section with an opened base side. Typically, the first flow field is of the same design as the second flow field.
-
FIG. 1 provides a schematic illustration of a fuel cell incorporating a flow field defining flow channels with improved pressure distribution; -
FIG. 2 is a perspective view of a metal plate used to form a fuel cell flow field; -
FIG. 3 is a top view a portion of a flow field defining an opening for inputting or outputting a reactant gases or coolant to a flow field; -
FIG. 4A is a cross section of a metal plate defining a tunnel with a curved cross section; -
FIG. 4B is a cross section of a metal plate defining a tunnel with a cross section having two lobes; -
FIG. 5A is a cross section of a metal plate defining a tunnel with straight sides and a curved top; -
FIG. 5B is a cross section of a metal plate defining a tunnel with straight sides and two lobes; -
FIG. 6 illustrates the basic design of a test coupon that was used to determine the pressures on the metal bead seal for various tunnel cross sections -
FIG. 7A provides a plot of the seal contact pressure for prior art flow channel; -
FIG. 7B provides a plot of the seal contact pressure for a flow channel having a round section; and -
FIG. 7C provides a plot of the seal contact pressure for a flow channel having a low trapezoidal cross section. - Reference will now be made in detail to presently preferred compositions, embodiments and methods of the present invention, which constitute the best modes of practicing the invention presently known to the inventors. The Figures are not necessarily to scale. However, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for any aspect of the invention and/or as a representative basis for teaching one skilled in the art to variously employ the present invention.
- Except in the examples, or where otherwise expressly indicated, all numerical quantities in this description indicating amounts of material or conditions of reaction and/or use are to be understood as modified by the word “about” in describing the broadest scope of the invention. Practice within the numerical limits stated is generally preferred. Also, unless expressly stated to the contrary: percent, “parts of,” and ratio values are by weight; the description of a group or class of materials as suitable or preferred for a given purpose in connection with the invention implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred; the first definition of an acronym or other abbreviation applies to all subsequent uses herein of the same abbreviation and applies mutatis mutandis to normal grammatical variations of the initially defined abbreviation; and, unless expressly stated to the contrary, measurement of a property is determined by the same technique as previously or later referenced for the same property.
- It is also to be understood that this invention is not limited to the specific embodiments and methods described below, as specific components and/or conditions may, of course, vary. Furthermore, the terminology used herein is used only for the purpose of describing particular embodiments of the present invention and is not intended to be limiting in any way.
- It must also be noted that, as used in the specification and the appended claims, the singular form “a,” “an,” and “the” comprise plural referents unless the context clearly indicates otherwise. For example, reference to a component in the singular is intended to comprise a plurality of components.
- The term “comprising” is synonymous with “including,” “having,” “containing,” or “characterized by.” These terms are inclusive and open-ended and do not exclude additional, unrecited elements or method steps.
- The phrase “consisting of” excludes any element, step, or ingredient not specified in the claim. When this phrase appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole.
- The phrase “consisting essentially of” limits the scope of a claim to the specified materials or steps, plus those that do not materially affect the basic and novel characteristic(s) of the claimed subject matter.
- The terms “comprising”, “consisting of”, and “consisting essentially of” can be alternatively used. Where one of these three terms is used, the presently disclosed and claimed subject matter can include the use of either of the other two terms.
- Throughout this application, where publications are referenced, the disclosures of these publications in their entireties are hereby incorporated by reference into this application to more fully describe the state of the art to which this invention pertains.
- With reference to
FIG. 1 , an idealized schematic cross section of a fuel cell that incorporates an embodiment of a fibrous sheet is provided. Proton exchange membrane (PEM)fuel cell 10 includes polymericion conducting membrane 12 disposed betweencathode catalyst layer 14 andanode catalyst layer 16.Fuel cell 10 also includes flow fields 18, 20 which definegas flow channels cathode catalyst layer 14 andanode catalyst layer 16, respectively. During operation of thefuel cell 10, a fuel such as hydrogen is feed toanode catalyst layer 16 throughgas flow channels 26 and an oxidant such as oxygen is feed tocathode catalyst layer 14 throughgas flow channels 24. Flow fields 18, 20 also definecooling channels 32 which are used to flow coolant through the flow field plates. It should be appreciated that flow fields 18, 20 are each typically formed from two metal plates are provided. For example, flowfield 18 is formed from channel-definingplates flow field 20 is formed from channel-definingplates metal plates FIG. 1 is an idealized schematic and thatgas flow channels embossing plates FIG. 1 also depicts the side sealing of the fuel cell in whichperipheral gasket 34 seals to embossments 36. Hydrogen ions are generated byanode catalyst layer 16 migrate through polymericion conducting membrane 12 were they react atcathode catalyst layer 14 to form water. This electrochemical process generates an electric current through a load connect to flowfield plates - With reference to
FIGS. 1, 2, 3A, and 3B schematic illustrations show that flow fields 18, 20 are each typically formed from two metal plates are provided. For example, flowfield 18 is formed from channel-definingplates flow field 20 is formed from channel-definingplates FIG. 2 is a perspective view of a metal plate that is typical of the design of embossedplates first metal bead 66 surrounds one or more of openings 42-52.First metal bead 66 is an embossment that defines a first channel 70. Typically, the liquid coolant flows or reactants through this channel. In a refinement, a soft material (e.g., elastomer, rubber, foam, etc.) is coated on the top ofmetal bead 66 to make a seal between adjacent flow fields (seeitem number 35 inFIG. 1 ). Plurality oftunnels 68 provides a passage into and out of thefirst metal bead 66. Eachtunnel 68 of the first plurality of tunnels has aninlet tunnel section 72 that leads to thefirst metal bead 66 and anoutlet tunnel section 74 that extends from thefirst metal bead 66 to provide coolant or reactant gases to flowchannels FIG. 2 also depicts acoolant flow channels 82 which is also defined by an embossment. - With reference to
FIG. 3 , a flow field defining an opening for inputting or outputting reactant gases or coolant to the flow fields is provided.First metal bead 66 surrounds openings 42-52.First metal bead 66 is an embodiment that defines a first channel 90. In a refinement, a soft material (e.g., elastomer, rubber, foam, etc.) is coated on the top ofmetal bead 66 to make a seal between adjacent flow fields. Plurality oftunnels 68 provides a passage into and out of thechannel 80 which is defined byfirst metal bead 66. Eachtunnel 68 of the first plurality of tunnels has aninlet tunnel section 72 that leads to the first channel 90 and an outlet tunnel section 94 that extends from thefirst channel 80 to provide a reactant gas or coolant to flowchannels - With reference to
FIG. 4A and 4B , schematic cross sections of a flow tunnel with a curved section is provided.FIG. 4A depictsflow tunnel 100 which is formed in any ofplates Flow tunnel 100 which has an upper wall that is has asingle arc 102 in cross section and anopen base 104.FIG. 4A also depicts channel-definingmetal bead 106 to whichtunnel 100 flows.Flow tunnel 100 provides a design for the tunnels of plurality oftunnels 68 ofFIG. 3A and of the plurality of tunnels 88 ofFIG. 3B . In particular, the cross section ofupper wall 102 is approximated by a section of the circumference of a circle. In a refinement, open base width w is from about 0.4 mm to about 3 mm.Flow tunnel 100 is also defined by a maximum height which is the perpendicular distance fromopen base 104 to the top of the channel. In a refinement, the maximum height h is from about 0.1 mm to about 2 mm. When a section offlow tunnel 100 is approximated by a portion of the circumference of a circle, the circle has a radius from about 0.2 to about 3 mm. -
FIG. 4B depictsflow tunnel 110 which is formed in any ofplates flow tunnel 110 has a cross section with at least twolobes Flow tunnel 110 has a base (e.g., imaginary or a wall) and a maximum height which is the perpendicular distance from theopen base 104 to the top of the channel.FIG. 4B also depicts channel-definingmetal bead 116 to whichtunnel 110 flows. In a refinement, open base width w is from about 0.4 mm to about 3mm. In a further refinement, the maximum height h is from about 0.1 mm to about 2 mm. -
FIG. 5A depicts a flow tunnel with straight sides and a curved top in cross section. In this refinement,flow tunnel 120 has a cross section with an uppercurved surface 122.Flow channel 120 has a wall angle α (i.e., angle betweenwall 124 and open base 126) is from 10 to 80 degrees.Flow channel 120 is defined by a base and a maximum height which is the perpendicular distance from the base to the top of the channel.FIG. 5A also depicts channel-definingmetal bead 128 to whichtunnel 120 flows. In a refinement, the base width is from about 0.4 mm to about 3 mm. In a further refinement, the maximum height h is from about 0.1 mm to about 3 mm. In a refinement,linear side 124 is from about 0.1 to 3 mm in length. -
FIG. 5B depicts a flow tunnel with straight sides and a multi-lobed top in cross section. In this refinement, flow channel 130 has a wall angle α is from 10 to 80 degrees. Flow channel 130 is defined by a base and a maximum height h which is the perpendicular distance from the open base to the top of the channel. In a refinement, the open base width w is from about 0.4 mm to about 3 mm. In a further refinement, the maximum height h is from about 0.1 mm to about 3 mm. In a refinement,linear side 124 is from about 0.1 to 3 mm in length. - In a variation, the tunnels of
FIGS. 4A, 4B, 5A, and 5B have a cross sectional area from about 0.005 to 3 mm2. In a refinement, the tunnels ofFIGS. 4A, 4B, 5A, and 5B have a cross sectional area from about 0.01 to 1 mm2. In still another refinement, the tunnels ofFIGS. 4A, 4B, 5A, and 5B have a cross sectional area from about 0.01 to 0.5 mm2. It should also be appreciated that the cross sectional area of the tunnels can vary along the flow direction. For example, the cross sectional area can be large near the inlet and outlet and small near the metal bead. -
FIG. 6 illustrates the basic design of a test coupon that was used to determine the pressures for various tunnel cross sections. Pressure fields were determined by finite element analysis using a compression height of 100 microns.Test coupon 140 includestunnels 142 andmetal sealing bead 144.FIG. 7A provides the pressures in a prior art channel. These channels show a pressure variation range of about 1.83 MPa.FIG. 7B provides the pressures in a channel with a round cross section. These channels show a pressure variation range of about 1.66 MPa.FIG. 7C provides the pressures in a channel with a short trapezoidal cross section. These channels show a pressure variation range of about 1.18 MPa. - While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments, variations, and refinements may be combined to form further embodiments of the invention.
Claims (20)
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US15/285,795 US10547064B2 (en) | 2016-10-05 | 2016-10-05 | Tunnel cross section for more uniformed contact pressure distribution on metal bead seal at the intersection between bead and tunnel |
CN201710912021.4A CN107994239B (en) | 2016-10-05 | 2017-09-29 | Flow channel cross-sectional design with more elastic contact pressure distribution on metal bead seal at intersection between bead and flow channel |
DE102017122905.1A DE102017122905A1 (en) | 2016-10-05 | 2017-10-02 | Tunnel cross section design for more uniform contact pressure distribution on a metal bead seal at the intersection between the bead and the tunnel |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US15/285,795 US10547064B2 (en) | 2016-10-05 | 2016-10-05 | Tunnel cross section for more uniformed contact pressure distribution on metal bead seal at the intersection between bead and tunnel |
Publications (2)
Publication Number | Publication Date |
---|---|
US20180097242A1 true US20180097242A1 (en) | 2018-04-05 |
US10547064B2 US10547064B2 (en) | 2020-01-28 |
Family
ID=61623794
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US15/285,795 Active 2037-10-23 US10547064B2 (en) | 2016-10-05 | 2016-10-05 | Tunnel cross section for more uniformed contact pressure distribution on metal bead seal at the intersection between bead and tunnel |
Country Status (3)
Country | Link |
---|---|
US (1) | US10547064B2 (en) |
CN (1) | CN107994239B (en) |
DE (1) | DE102017122905A1 (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10211473B2 (en) * | 2016-11-21 | 2019-02-19 | GM Global Technology Operations LLC | Reduction of pressure variation with stamped embossment at bead neighbors |
US10355289B2 (en) * | 2017-02-06 | 2019-07-16 | GM Global Technology Operations LLC | Plate structure for a fuel cell |
WO2020195002A1 (en) * | 2019-03-28 | 2020-10-01 | Nok株式会社 | Fuel cell gasket |
JP2020177737A (en) * | 2019-04-15 | 2020-10-29 | トヨタ自動車株式会社 | Separator for fuel cell |
US11329296B2 (en) * | 2019-04-10 | 2022-05-10 | GM Global Technology Operations LLC | Displacement absorption tunnels for circular beads |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE202019101145U1 (en) * | 2019-02-28 | 2020-05-29 | Reinz-Dichtungs-Gmbh | Separator plate for an electrochemical system |
Family Cites Families (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6017648A (en) * | 1997-04-15 | 2000-01-25 | Plug Power, L.L.C. | Insertable fluid flow passage bridgepiece and method |
EP1160900A3 (en) * | 2000-05-26 | 2007-12-12 | Kabushiki Kaisha Riken | Embossed current collector separator for electrochemical fuel cell |
JP3751911B2 (en) * | 2002-07-02 | 2006-03-08 | 松下電器産業株式会社 | Polymer electrolyte fuel cell and method of manufacturing separator plate thereof |
US8371587B2 (en) * | 2008-01-31 | 2013-02-12 | GM Global Technology Operations LLC | Metal bead seal for fuel cell plate |
JP4420960B2 (en) * | 2008-05-13 | 2010-02-24 | シャープ株式会社 | Fuel cell and fuel cell layer |
DE102008052945B4 (en) * | 2008-10-23 | 2014-06-12 | Staxera Gmbh | Fuel cell stack and process for its production |
EP2224524B1 (en) * | 2009-02-12 | 2017-04-19 | Belenos Clean Power Holding AG | Fuel cell structure and separator plate for use therein |
US8802326B2 (en) * | 2010-11-23 | 2014-08-12 | GM Global Technology Operations LLC | Fuel cell separator plate |
CN104051771B (en) * | 2013-03-15 | 2018-11-02 | 福特全球技术公司 | Fuel cell pack and vehicle including it |
US9362574B2 (en) * | 2014-01-23 | 2016-06-07 | GM Global Technology Operations LLC | PEM fuel cell seal design and method for manufacture |
DE202014004456U1 (en) * | 2014-05-23 | 2015-05-28 | Reinz-Dichtungs-Gmbh | Metallic bipolar plate with spring-back sealing arrangement and electrochemical system |
CN104900894B (en) * | 2015-04-14 | 2018-02-02 | 中国东方电气集团有限公司 | The metal polar plate of fuel cell, the metal double polar plates of fuel cell, fuel cell |
US20170229717A1 (en) * | 2016-02-09 | 2017-08-10 | GM Global Technology Operations LLC | Robust fuel cell stack sealing designs using thin elastomeric seals |
-
2016
- 2016-10-05 US US15/285,795 patent/US10547064B2/en active Active
-
2017
- 2017-09-29 CN CN201710912021.4A patent/CN107994239B/en active Active
- 2017-10-02 DE DE102017122905.1A patent/DE102017122905A1/en active Pending
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10211473B2 (en) * | 2016-11-21 | 2019-02-19 | GM Global Technology Operations LLC | Reduction of pressure variation with stamped embossment at bead neighbors |
US10355289B2 (en) * | 2017-02-06 | 2019-07-16 | GM Global Technology Operations LLC | Plate structure for a fuel cell |
WO2020195002A1 (en) * | 2019-03-28 | 2020-10-01 | Nok株式会社 | Fuel cell gasket |
US11329296B2 (en) * | 2019-04-10 | 2022-05-10 | GM Global Technology Operations LLC | Displacement absorption tunnels for circular beads |
JP2020177737A (en) * | 2019-04-15 | 2020-10-29 | トヨタ自動車株式会社 | Separator for fuel cell |
JP7120136B2 (en) | 2019-04-15 | 2022-08-17 | トヨタ自動車株式会社 | Separator for fuel cell |
Also Published As
Publication number | Publication date |
---|---|
DE102017122905A1 (en) | 2018-04-05 |
US10547064B2 (en) | 2020-01-28 |
CN107994239B (en) | 2021-06-22 |
CN107994239A (en) | 2018-05-04 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US10547064B2 (en) | Tunnel cross section for more uniformed contact pressure distribution on metal bead seal at the intersection between bead and tunnel | |
US6348280B1 (en) | Fuel cell | |
US6974648B2 (en) | Nested bipolar plate for fuel cell and method | |
US7759014B2 (en) | Fuel cell having a seal member | |
JP5197995B2 (en) | Fuel cell | |
US8003273B2 (en) | Polymer electrolyte fuel cell and fuel cell sealing member for the same | |
CN108091900B (en) | Pressure variation reduction by embossing in the vicinity of the flange | |
US20180131016A1 (en) | Metal bead seal tunnel arrangement | |
JP2001297779A (en) | Fuel cell system | |
CA2542355C (en) | One piece bipolar plate with spring seals | |
US9705139B2 (en) | Printed multi-function seals for fuel cells | |
US20180123144A1 (en) | Design of tunnel layout for a more uniformed contact pressure distribution at the intersection between metal bead seal and tunnel | |
US10490829B2 (en) | Method for manufacturing a fuel cell | |
US10297811B2 (en) | Fuel cell stack | |
US20080102334A1 (en) | Pressure relief feature for a fuel cell stack | |
US8298714B2 (en) | Tunnel bridge with elastomeric seal for a fuel cell stack repeating unit | |
US7261124B2 (en) | Bipolar plate channel structure with knobs for the improvement of water management in particular on the cathode side of a fuel cell | |
US9362574B2 (en) | PEM fuel cell seal design and method for manufacture | |
US20240097150A1 (en) | Bipolar plate for an electrochemical cell, arrangement of electrochemical cells, and method for operating an arrangement of electrochemical cells | |
JP4606038B2 (en) | POLYMER ELECTROLYTE FUEL CELL AND METHOD OF OPERATING THE SAME | |
CN102714321A (en) | Fuel cell and vehicle equipped with fuel cell | |
US20190097248A1 (en) | Fuel cell stack | |
JP2005071955A (en) | Fuel cell | |
US10964956B2 (en) | Fuel cell stack assembly | |
JP2006210212A (en) | Polymer electrolyte fuel cell |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: GM GLOBAL TECHNOLOGY OPERATIONS LLC, MICHIGAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:XU, SIGUANG;YANG, XI;CHAPMAN, IVAN D.;AND OTHERS;REEL/FRAME:039945/0226 Effective date: 20161003 |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: RESPONSE TO NON-FINAL OFFICE ACTION ENTERED AND FORWARDED TO EXAMINER |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: NON FINAL ACTION MAILED |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: RESPONSE TO NON-FINAL OFFICE ACTION ENTERED AND FORWARDED TO EXAMINER |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: NOTICE OF ALLOWANCE MAILED -- APPLICATION RECEIVED IN OFFICE OF PUBLICATIONS |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: NOTICE OF ALLOWANCE MAILED -- APPLICATION RECEIVED IN OFFICE OF PUBLICATIONS |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |
|
MAFP | Maintenance fee payment |
Free format text: PAYMENT OF MAINTENANCE FEE, 4TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1551); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY Year of fee payment: 4 |